The present invention generally relates to the field of liquid-sensitive actuators for actuating a device upon immersion in a liquid. More particularly, the present invention is directed to a liquid activated buckle release mechanism for safety belt harnesses and restraint devices used in moving crafts such as airplanes, boats, land based vehicles and the like.
At the present time, approximately 90% of all military and civilian helicopter restraint devices employ a seat harness with a rotary buckle mechanism as illustrated in FIG. 1. As FIG. 1 shows, a seat strap 1 is routed between the crew member or passenger's legs. One end of strap 1 is bolted to the seat pan on which the crew member sits and the other end is attached to a rotary buckle 4. Shoulder straps 2 and lap belt straps 3 are inserted into rotary buckle 4 and are locked into place. In order to release straps 2 and 3 from buckle 4 so that the crewman can egress the aircraft, the crew member must rotate a buckle release handle 5.
When a crash of the aircraft or ditching in water occurs, the helicopter will, in most cases, roll over to an inverted position and sink. The ingress of water and the panic of the crew member makes it difficult to locate and operate release handle 5 to free himself from the seat harness and perform an emergency egress maneuver. In many instances, the crew member is trapped and drowns. The crew member may also be unconscious or too injured as a result of the crash to operate the release handle. Thus, a crew mate will not only have to locate and operate the release handle for his own harness, he must also locate and operate the release handle for the injured crewman as well. The time lost in doing so further endangers the lives of all involved.
Water craft also represent another cause for concern with respect to rapid release of safety belts and restraint devices in the event of an emergency. The concern is particularly great with respect to motor boats. In an accident where the boat capsizes or loses its structural integrity, those on board must quickly release themselves from any restraint systems. As in the case of the downed crewmen in the helicopter discussed above, they may be unable to do so with out the assistance of others.
There are many other circumstances in which life-saving restraint devices can become a danger to life. Even the safety-belt in a typical automobile can be difficult to unbuckle during an emergency. The need for an automatic release of the buckle is particularly desirable where there is heavy vehicle traffic around large bodies of water such as lakes, rivers, ponds and the like. Occupants of a vehicle which accidentally plunges into these bodies of water are confronted with the some dangers described above with respect to crewman in aircraft. Moreover, infants who are buckled into child safety seats are particularly at risk in these situations.
Accordingly, there is a great need for a buckle release mechanism which can be manually and automatically operated in an emergency situation.